Occipital Nerve Field Transcranial Direct Current Stimulation Normalizes Imbalance Between Pain Detecting and Pain Inhibitory Pathways in Fibromyalgia

Abstract

Occipital nerve field (OCF) stimulation with subcutaneously implanted electrodes is used to treat headaches, more generalized pain, and even failed back surgery syndrome via unknown mechanisms. Transcranial direct current stimulation (tDCS) can predict the efficacy of implanted electrodes. The purpose of this study is to unravel the neural mechanisms involved in global pain suppression, mediated by occipital nerve field stimulation, within the realm of fibromyalgia. Nineteen patients with fibromyalgia underwent a placebo-controlled OCF tDCS. Electroencephalograms were recorded at baseline after active and sham stimulation. In comparison with healthy controls, patients with fibromyalgia demonstrate increased dorsal anterior cingulate cortex, increased premotor/dorsolateral prefrontal cortex activity, and an imbalance between pain-detecting dorsal anterior cingulate cortex and pain-suppressing pregenual anterior cingulate cortex activity, which is normalized after active tDCS but not sham stimulation associated with increased pregenual anterior cingulate cortex activation. The imbalance improvement between the pregenual anterior cingulate cortex and the dorsal anterior cingulate cortex is related to clinical changes. An imbalance assumes these areas communicate and, indeed, abnormal functional connectivity between the dorsal anterior cingulate cortex and pregenual anterior cingulate cortex is noted to be caused by a dysfunctional effective connectivity from the pregenual anterior cingulate cortex to the dorsal anterior cingulate cortex, which improves and normalizes after real tDCS but not sham tDCS. In conclusion, OCF tDCS exerts its effect via activation of the descending pain inhibitory pathway and de-activation of the salience network, both of which are abnormal in fibromyalgia.

Is Transcranial Direct Current Stimulation (tDCS) Effective for the Treatment of Pain in Fibromyalgia? A Systematic Review and Meta-Analysis

“…Anodal tDCS was administered at an intensity of 2 mA for 11 studies, 6,15,17,23,24,33,37,38,47,51,52 1.5 mA for 2 studies, 43,50 and 1 mA for one study. 30 The target sites were 1) left primary motor cortex (M1; corresponding to C3 on the 10−20 system for electrode placement in electroencephalography) with the cathode placed over right supraorbital (SO) cortex 17,23,24,30,37,38,47,51 ; 2) right Dorsolateral Prefrontal Cortex (DLPFC; corresponding to F4) with the cathode placed over left DLPFC (corresponding to F3) 6 or anode over left DLPFC and cathode over right DLPFC 50 or right SO 33 ; and 3) right occipital nerve stimulation with the cathode placed over the left (corresponding to right and left side of the C2 dermatome) 6,15 or left occipital nerve stimulation with the cathode placed over the right. 50 In only one study was the reference electrode placed in an extra-cephalic site on the contralateral arm.…”

“…17,23,24,33,38,51 For the sham condition, all but one study reported using the same electrode montage as the active condition with the same current density, which lasted for durations of between 10 and 43 seconds. Eleven studies applied the sham stimulation at the start of the session only, 6,15,17,24,37,38,43,47,[50][51][52] 2 applied it at both the start and end of the session, 23,33 and 1 did not apply any stimulation. 30…”

“…Data from pain intensity could be pooled from 9 trials (n = 264). We were unable to include data from 15,37,43,50,51 because pain intensity data were not reported or available upon request.…”

Greater Occipital Nerve Stimulation Boosts Associative Memory in Older Individuals: A Randomized Trial

“…Previous findings by our group show that participants are unable to tell whether they received real or sham stimulation following this protocol. 18 Saliva Collection. Participants' saliva was collected 4 times during the experiment: before stimulation, immediately after stimulation, 7 days after stimulation, and 28 days after stimulation.…”

Are 10 kHz Stimulation and Burst Stimulation Fundamentally the Same?

“…Indeed cingulotomies can reduce pain suffering without reducing pain intensity . It is clear that the ascending pain evoking and descending pain inhibitory pathways need to interact is some way, and it has been suggested that these interactions are dynamically changing depending on the context , and that it is ultimately the balance between pain input and pain suppression that results in whether someone feels pain or not, both in neuropathic , and fibromyalgia pain . The exact anatomical and functional connectomics in pain have yet to be unraveled, but both structural (i.e., anatomical) and functional (i.e., resting state) MRI studies in pain demonstrate complex interactions between somatosensory cortex, cingulate cortex, insula, amygdala, thalamus and frontal cortex .…”